Evaporation - bloody hell!

[rushn]

My distillate leaves my still reasonably hot. I collected 150ml foreshots on my last run in a 250ml beaker - spot on the measurement marker on the beaker. I looked back around 1hr later, and the level in the (uncovered) beaker had dropped around 15mls! I couldn't believe my eyes! I quickly placed lids on my hearts jars ;-)

I did a forum search on evaporation which didn't turn up much. Is this the real deal, and something to be genuinely wary of? I imagine any evaporation would reduce the ABV of collected spirit. I assume evap would reduce when the spirit cools to ambient?

[Sam.]

Alcohol evaporates mate, to what degree is up to the climate. Rough area that you are located?

[Wellsy]

7% in an hour seems high to me. What temp was the spirit, and were the cuts jars sitting under a heater.
Now for the basic was it plugged in question, was the cuts jar sitting on the same place in the same orientation for both measurements, I am amazed at how unlevel some surfaces are and a 180 degree spin of the measurement jar makes a big difference

[Amberale]

I don’t know how your still works but I adjust my PC water rate so my product comes out cold.
I use a bit more water(it’s recycled anyway) but no free alcohol vapour or explosions. :O

[bluc]

Def seems excessive what temp does spirit leave pc?

[rushn]

Alcohol evaporates mate, to what degree is up to the climate. Rough area that you are located?

Southern Riverina, NSW. Was a cool day, around 16 degrees.

[rushn]

7% in an hour seems high to me. What temp was the spirit, and were the cuts jars sitting under a heater.
Now for the basic was it plugged in question, was the cuts jar sitting on the same place in the same orientation for both measurements, I am amazed at how unlevel some surfaces are and a 180 degree spin of the measurement jar makes a big difference

I reckon the distillate was around 40 to 45 degrees leaving the PC. I have my collection jars sitting on a laundry bench, which is level. No heater anywhere near the still.

[rushn]

I don’t know how your still works but I adjust my PC water rate so my product comes out cold.
I use a bit more water(it’s recycled anyway) but no free alcohol vapour or explosions. :O

I was running water straight from the cold water tap, and had the flow higher than needed - I do this in the event someone flushes the loo, etc. The water exiting the PC was quite cool to the touch.

[rushn]

Def seems excessive what temp does spirit leave pc?

It’s quite hot. I haven’t measured the temp (I’ll do that next run). It’s not hot enough that I can’t put my finger in it, so at a guess I’d say it’s around 40 to 45 degrees.

Could it be that the foreshots contains all the lighter alcohols which would evaporate off quicker at the PC output temp?

[BigRig]

The alcoengine bokas are poor at cooling the distillate. It is barely sufficient to knock vapour down to liquid but thats it. It will come off at 40-50c.

With mine I would collect the booze, lid on and into the fridge. Once it cooled i would then air overnight.

You may need to do the same thing otherwise u will lose a lot to evaporation.

[RuddyCrazy]

When I do my cuts using my 2" pot still I use 6 off 50ml beakers for the heads and later for the tails, then a paper towel is placed over for the cuts to air for 2 days. Now the loss to the angels is about 10% and we don't want to drink that anyway so the angels do it for us :handgestures-thumbupleft: I do find by leaving the cuts for a couple of days the smell and taste is completely different to the smell and taste on the day of distilling so for making a quality drop the Angels MUST have their share.

Cheers Bryan

[rushn]

The alcoengine bokas are poor at cooling the distillate. It is barely sufficient to knock vapour down to liquid but thats it. It will come off at 40-50c.

With mine I would collect the booze, lid on and into the fridge. Once it cooled i would then air overnight.

You may need to do the same thing otherwise u will lose a lot to evaporation.

Thanks mate. Yeah, I did another run yesterday and did exactly as you mention, except I didn’t place in the fridge. The temperature yesterday was almost fridge-like, so nature cooled the jars for me.

Cheers

[rushn]

Now the loss to the angels is about 10%

Thanks RC. So I’m not crazy then!

[Professor Green]

I made a cheap secondary cooling condenser for my boka to make sure the product was cool when I collected it. Just a simple worm design with a copper coil in a bucket. Worked a treat.

[scythe]

I would guess you were closer to 60°c
That's what my hot water comes out at and I can't keep my finger in it.

50-60°c is on the dangerous end of the temperature range.
I would build an extra PC for your still.
15% loss in 1hr is a lot compared to 10% over 24-48hrs.

[WhiskeySour]

There could be something else at play if your temp is indeed closer to 60c.
Liquids expand in volume when heated, and contract when cooled. The rate of expansion/contraction increases as temp is increased also
If your spirit is coming off the still hot and cooling rapidly (on a 16 degree day a cold bench will suck a reasonable amount of heat out of the jar), you will likely be seeing a drop in level due to contraction of the liquid. Probably getting increased evap as well as the higher temp
I'm with Scythe, a more efficient PC might be worthwhile looking into
WS

[NFI]

From a complete nooby, you could try covering one cut jar and leave another uncovered you will be able to tell how much is contraction of the fluid and how much is evaporation. From my Precious Metal recovery days, you could try covering the jar with an upturned funnel (glass of course) to reduce evaporation losses whist still breathing.
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[rushn]

Cheers for the responses. I checked the product temp, and it's at or around 50C.

For my last run, I sat my collection jars in a wide, shallow tray filled with water and ice. This helped with taking the temp down quickly. It didn't happen this time, but I'm almost certain I'll get some glass fracturing with the temp difference if I keep this up, so not something I think I'll do again! I do have a heap of borosilicate beakers that I could use, although they have no lids.

I agree, I need a PC to cool the output, but don't have the expertise to manufacture one. I like the worm-in-bucket idea though.

Thanks guys and gals.

[scythe]

Yeah a worm sounds good.
Anything is better that 50°c distillate, that's quite a hazard.

[BSC_Kilby]

Yeah a worm sounds good.
Anything is better that 50°c distillate, that's quite a hazard.

Absolutely. I'd never be happy seeing spirit come off above 20 degrees C, to be honest.